rfkill: do not allow userspace to override ALL RADIOS OFF

SW_RFKILL_ALL is the "emergency power-off all radios" input event.  It must
be handled, and must always do the same thing as far as the rfkill system
is concerned: all transmitters are to go *immediately* offline.

For safety, do NOT allow userspace to override EV_SW SW_RFKILL_ALL OFF.  As
long as rfkill-input is loaded, that event will *always* be processed, and
it will *always* force all rfkill switches to disable all wireless
transmitters, regardless of user_claim attribute or anything else.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Cc: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

3 files changed, 51 insertions, 15 deletions

diff --git a/net/rfkill/rfkill-input.c b/net/rfkill/rfkill-input.c
index d285f9a9d829..5d4c8b2446f7 100644
--- a/net/rfkill/rfkill-input.c
+++ b/net/rfkill/rfkill-input.c
@@ -43,11 +43,26 @@ static void rfkill_task_handler(struct work_struct *work)
 	mutex_unlock(&task->mutex);
 }
 
+static void rfkill_task_epo_handler(struct work_struct *work)
+{
+	rfkill_epo();
+}
+
+static DECLARE_WORK(epo_work, rfkill_task_epo_handler);
+
+static void rfkill_schedule_epo(void)
+{
+	schedule_work(&epo_work);
+}
+
 static void rfkill_schedule_set(struct rfkill_task *task,
 				enum rfkill_state desired_state)
 {
 	unsigned long flags;
 
+	if (unlikely(work_pending(&epo_work)))
+		return;
+
 	spin_lock_irqsave(&task->lock, flags);
 
 	if (time_after(jiffies, task->last + msecs_to_jiffies(200))) {
@@ -63,6 +78,9 @@ static void rfkill_schedule_toggle(struct rfkill_task *task)
 {
 	unsigned long flags;
 
+	if (unlikely(work_pending(&epo_work)))
+		return;
+
 	spin_lock_irqsave(&task->lock, flags);
 
 	if (time_after(jiffies, task->last + msecs_to_jiffies(200))) {
@@ -114,21 +132,20 @@ static void rfkill_event(struct input_handle *handle, unsigned int type,
 		switch (code) {
 		case SW_RFKILL_ALL:
 			/* EVERY radio type. data != 0 means radios ON */
-			rfkill_schedule_set(&rfkill_wwan,
-					    (data)? RFKILL_STATE_ON:
-						    RFKILL_STATE_OFF);
-			rfkill_schedule_set(&rfkill_wimax,
-					    (data)? RFKILL_STATE_ON:
-						    RFKILL_STATE_OFF);
-			rfkill_schedule_set(&rfkill_uwb,
-					    (data)? RFKILL_STATE_ON:
-						    RFKILL_STATE_OFF);
-			rfkill_schedule_set(&rfkill_bt,
-					    (data)? RFKILL_STATE_ON:
-						    RFKILL_STATE_OFF);
-			rfkill_schedule_set(&rfkill_wlan,
-					    (data)? RFKILL_STATE_ON:
-						    RFKILL_STATE_OFF);
+			/* handle EPO (emergency power off) through shortcut */
+			if (data) {
+				rfkill_schedule_set(&rfkill_wwan,
+						    RFKILL_STATE_ON);
+				rfkill_schedule_set(&rfkill_wimax,
+						    RFKILL_STATE_ON);
+				rfkill_schedule_set(&rfkill_uwb,
+						    RFKILL_STATE_ON);
+				rfkill_schedule_set(&rfkill_bt,
+						    RFKILL_STATE_ON);
+				rfkill_schedule_set(&rfkill_wlan,
+						    RFKILL_STATE_ON);
+			} else
+				rfkill_schedule_epo();
 			break;
 		default:
 			break;
diff --git a/net/rfkill/rfkill-input.h b/net/rfkill/rfkill-input.h
index 4dae5006fc77..f63d05045685 100644
--- a/net/rfkill/rfkill-input.h
+++ b/net/rfkill/rfkill-input.h
@@ -12,5 +12,6 @@
 #define __RFKILL_INPUT_H
 
 void rfkill_switch_all(enum rfkill_type type, enum rfkill_state state);
+void rfkill_epo(void);
 
 #endif /* __RFKILL_INPUT_H */
diff --git a/net/rfkill/rfkill.c b/net/rfkill/rfkill.c
index dd1c3f18f31d..7d07175c407f 100644
--- a/net/rfkill/rfkill.c
+++ b/net/rfkill/rfkill.c
@@ -182,6 +182,24 @@ void rfkill_switch_all(enum rfkill_type type, enum rfkill_state state)
 EXPORT_SYMBOL(rfkill_switch_all);
 
 /**
+ * rfkill_epo - emergency power off all transmitters
+ *
+ * This kicks all rfkill devices to RFKILL_STATE_OFF, ignoring
+ * everything in its path but rfkill_mutex.
+ */
+void rfkill_epo(void)
+{
+	struct rfkill *rfkill;
+
+	mutex_lock(&rfkill_mutex);
+	list_for_each_entry(rfkill, &rfkill_list, node) {
+		rfkill_toggle_radio(rfkill, RFKILL_STATE_OFF, 1);
+	}
+	mutex_unlock(&rfkill_mutex);
+}
+EXPORT_SYMBOL_GPL(rfkill_epo);
+
+/**
  * rfkill_force_state - Force the internal rfkill radio state
  * @rfkill: pointer to the rfkill class to modify.
  * @state: the current radio state the class should be forced to.